Follicular development in a 7-day versus 4-day hormone-free interval with an oral contraceptive containing 20 mcg ethinyl estradiol and 1 mg norethindrone acetate.

Abstract

BACKGROUND:

Combined oral contraceptive (COC) formulations with 20 mcg ethinyl estradiol (EE) have a greater incidence of ovarian hormone production and follicular development, which can be managed by shortening the number of hormone-free days per COC cycle. This study evaluates differences in follicular development during a 7-day versus 4-day hormone-free interval in a COC regimen with 20 mcg EE and 1 mg norethindrone acetate.

STUDY DESIGN:

Forty-one healthy women were randomized in an open-label fashion to this formulation in either a 24/4 or a 21/7 day regimen for three cycles. Estradiol, progesterone, follicle-stimulating hormone, luteinizing hormone and inhibin B were measured daily from Cycle 2, Day 21 to Cycle 3, Day 3 and on Day 7 of Cycle 3. Follicular diameter and Hoogland score were calculated on Cycle 2, Days 21, 24 and 28 and Cycle 3, Days 3 and 7.

RESULTS:

Sixty-six percent of subjects in the 21/7 group and 70% of the subjects in the 24/4 group developed a follicle greater than 10 mm diameter. Ovarian steroid hormone levels, Hoogland scores and bleeding patterns were not statistically significant between the groups.

CONCLUSION:

In contrast to prior studies, this analysis suggests no difference in follicle development or bleeding patterns among women receiving a 21/7 or 24/4 regimen of a 20-mcg EE/1-mg norethindrone acetate COC.

• Authors: Radhika D Rible, DeShawn Taylor, Melissa L Wilson, Frank Z Stanczyk, Daniel R Mishell Jr
• Journal: Contraception (Contraception) Vol. 79 Issue 3 Pg. 182-8 (Mar 2009) ISSN: 1879-0518 [Electronic] United States
• PMID: 19185670 (Publication Type: Comparative Study, Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)

Chemical References

• Contraceptives, Oral, Combined
• inhibin B
• Ethinyl Estradiol
• Progesterone
• Estradiol
• Inhibins
• Luteinizing Hormone
• Follicle Stimulating Hormone
• Norethindrone Acetate
• Norethindrone

Topics

• Adolescent
• Adult
• Contraceptives, Oral, Combined (administration & dosage)
• Drug Administration Schedule
• Endometrium (drug effects)
• Estradiol (blood)
• Ethinyl Estradiol (administration & dosage)
• Female
• Follicle Stimulating Hormone (blood)
• Humans
• Inhibins (blood)
• Luteinizing Hormone (blood)
• Menstruation (drug effects)
• Middle Aged
• Norethindrone (administration & dosage, analogs & derivatives)
• Norethindrone Acetate
• Ovarian Follicle (diagnostic imaging, drug effects, growth & development)
• Progesterone (blood)
• Ultrasonography
• Young Adult